Problem: Simplify the following expression: ${-r+4(-9r-4)}$
Solution: Distribute the ${4}$ into the parentheses: $ -r + {4(}\gray{-9r-4}{)} $ $ -r {-36r-16} $ Combine the $r$ terms: $ {-r - 36r} - 16$ $ {-37r} - 16$ The simplified expression is $-37r-16$